Stringing device for sports racket

ABSTRACT

A stringing device for a sports racket includes a base and a cleat. The base has a pair of opposing side ends, an upper surface and a bottom surface. The base further has a guiding groove with an open end and a string engaging surface. The cleat extends downward from the bottom surface of the base and has a guiding channel with an inlet and an outlet. The inner diameter of the guiding channel is larger than the outer diameter of the racket string. The string engaging surface of the guiding groove has a suspending portion corresponding to the inlet of the guiding channel for guiding a racket string entering/exiting from the open end of the guiding groove to thread through the guiding channel from the inlet or outlet thereof without touching the inner wall of the guiding channel.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to strung sports rackets, for example tennis, squash or badminton rackets, and more particularly to a stringing device for strung sports rackets.

2. Description of the Related Art

It is well known that the most conventional sports racket has a common, general construction in which a head coupled to a grip via a yoke has a substantially oval shape defining a face formed by a latticework of strings. The head of such prior art rackets is usually constructed to have a set of string holes to be passed by the strings to form the latticework. This effectively divides the strings into individual and isolated string chords which span the head. Such an anchored string relationship causes high dynamic tension along individual string chords during impact with resulting a poor performance of a sport racket, including a smaller string deflection and shorter dwell time.

U.S. Pat. Nos. 4,591,165 and 4,930,782 to Karakal teach a rigid rocker member installed between the string and the supporting portion of the racket head to transmit tension from one string chord to an associated string chord. This structure eliminates frictional contact between the string chords and the racket head and causes tension in the impacting string chords to be transferred to other or all additional string chords in the racket. The result is that the sports racket with such a rocker member can provide greater efficiency of energy storage and allows more of the kinetic energy of the ball to be stored in the racket during impact.

However, such an assembly still has problems. For instance, it was difficult to retain individual rockers in place during stringing. A broken string could result in some or all of the rockers being lost from the racket, and possibly scattered over a playing court. Restringing involved the same problems as original assembly, while also requiring the need for the user or repairer to stock spare rockers to replace those lost after a string break. In addition, while the rocker member rocks in response to different amounts of force applied by the associated string chords, as shown in FIG. 11 of U.S. Pat. No. 4,930,782, the string chords passing through the string holes of the racket will contact or be secured against the inner-wall thereof. This means that the friction between the string chords and the racket head will not be eliminated by the rocker member and the tension in the impacting string chords cannot be smooth and averagely transferred to other string chords in the racket.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a stringing device for a sports racket which can effectively reduce the friction between the string chords and the head of the sports racket and in the same time simplify the stringing operation of the sports racket.

To achieve this object, a stringing device embodied according to the present invention includes an elongated base and a cleat extending from the base. The device may be made of light weight and rigid materials, such as aluminum alloy, titanium alloy or FRP. The base has a pair of opposing longitudinal side ends, a longitudinal upper surface and a longitudinal bottom surface opposed to the upper surface. Each of the surfaces extends between the opposing longitudinal side ends. The base further has a guiding groove running longitudinally along the upper surface. The groove has an open end and a string engaging surface. The cleat extends downward from the bottom surface of the base and has an outer diameter being slightly smaller than the inner diameter of the string holes of a sports racket so as to be inserted thereinto when the stringing operation is proceeded. The cleat further has a guiding channel through which a racket string threads. The guiding channel has an inlet connected with the string engaging surface of the guiding groove of the base and an outlet opposed to the inlet. The inner diameter of the guiding channel is larger than the outer diameter of the racket string. In addition, the string engaging surface of the guiding groove of the base has a suspending portion corresponding to the inlet of the guiding channel for guiding a racket string entering/exiting from the open end of the guiding groove to thread through the guiding channel from the inlet or outlet thereof without touching the inner wall of the guiding channel. Specially, the suspending portion may be a bulge or a horn projecting from the string engaging surface and extending into the inlet of the guiding channel so that the racket string is in a suspending way to thread through the guiding channel without touching the inner wall thereof.

The objects of the present invention are also achieved with the aid of a stringing device which comprises an elongated base and a pair of cleats. The base includes opposing longitudinal ends, a longitudinal upper surface and a longitudinal bottom surface opposed from said upper surface, each of said surfaces extending between said opposing longitudinal ends. The base further has a guiding groove running longitudinally along the upper surface thereof. The guiding groove has opposing longitudinal open ends and a string engaging surface disposed between the open ends for engaging and receiving a string which is looped thereover. Each of the cleats is respectively disposed at each of the opposing longitudinal ends of the base and extends downward from the bottom surface of the base. Each of the cleats also has a guiding channel through which a racket string threads. The guiding channel has an inlet connected with the string engaging surface and an outlet opposed to the inlet. The inner diameter of the guiding channel is larger than the outer diameter of a racket string threading therethrough. Furthermore, the string engaging surface of the guiding groove of the base is constructed to have a pair of suspending portions, each of the suspending portions corresponding respectively to the inlet of the guiding channel of each of the cleats for guiding a racket string to thread through the guiding channel without touching the inner wall thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments of the present invention will be described below with reference to the drawings, wherein:

FIG. 1 is a front view of a sports rackets with portions broken away to illustrate features of the present invention;

FIG. 2 is a perspective view of a first embodiment of the present invention;

FIG. 3 is an enlarged view of A portion of FIG. 1;

FIG. 4 is a perspective view of a second embodiment of the present invention;

FIG. 5 is an enlarged view of a broken portion of a sports racket equipped with the second embodiment shown in FIG. 4;

FIG. 6 is a perspective view of a third embodiment of the present invention;

FIG. 7 is an enlarged view of a broken portion of a sports racket equipped with the third embodiment shown in FIG. 6;

FIG. 8 is a perspective view of a fourth embodiment of the present invention; and

FIG. 9 is an enlarged view of a broken portion of a sports racket equipped with the fourth embodiment shown in FIG. 8.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a tennis racket equipped with a stringing device embodied according to the present invention to form a string face. The racket is generally designated by the reference numeral 90. Tennis racket 90 includes an elongated handle 92, a head frame 94 connected to one end of handle 92 and a handgrip 96 connected to another end of handle 92. Head frame 94 is planar with handle 92. Tennis racket 90 may be made from fiber reinforced plastic materials or any suitable materials.

Head frame 94 includes an outer surface 942, an inner outer surface 944 and an annular channel 946 extending along outer surface 942. Inner surface 944 defines a string opening 98. A plurality of string holes are formed through head frame 94 into string opening 98. String 100 is threaded through head frame 94 using string holes to form an impacting string face.

String holes are usually arranged in two groups. A first, longitudinal group of string holes 102 may be formed through head frame 94 along parallel longitudinal axes and spaced across head frame 94 to receive portions of the longitudinal string chords. A second or transverse group of string holes 104 may be formed through head frame 94 along transverse axes and preferably parallel to one another to receive portions of the transverse string chords.

A stringing device 10 embodied according to the present invention is shown in detail in FIGS. 2-3. Stringing device 10 may be made of any suitable rigid materials. In this embodiment, it is made of aluminum alloy.

Stringing device 10 includes an elongated base 12 and a pair of cleats 14. Base 12 has a longitudinal upper surface 16, a longitudinal bottom surface 18 and a guiding groove 20 running longitudinally along upper surface 16. Guiding groove 20 has a pair of opposing longitudinal open ends 202 and a string engaging curved surface 204 disposed between open ends 202 for engaging and receiving a string chord 106 which is looped thereover.

Cleats 14 are arranged to be inserted into two adjacent string holes, although other arrangements are possible. Each of cleats 14 respectively extends downward from bottom surface 18 of base 12 and has a guiding channel 142 with an inlet 144, an outlet 146 opposed to inlet 144 and an inner diameter being larger than the outer diameter of racket string 100 so that it can thread therethrough.

Furthermore, string engaging surface 204 of guiding groove 20 is constructed to have a pair of bulges 30. Each of bulges 30 has a curved bearing surface 302 and is arranged to correspond to inlet 144 of guiding channel 142 of each of cleats 14 for guiding a racket string 100 to thread through guiding channel 142 without touching inner wall 148 thereof. Specially, each of bulges 30 extends slightly into inlet 144 of guiding channel 142 so that the diameter of inlet 144 is smaller than that of outlet 144. This will always ensure the best possible suspending of the string threading through guiding channel 142 along the axis thereof without thereby touching inner wall 148 thereof.

Stringing device 10 can be used on a tennis racket or other appropriate strung sports rackets. In this embodiment, device 10 is mounted on racket 90 in such a way that base 12 is installed between string chord 106 and the bottom surface of annular channel 946 of head frame 94 and each of cleats 14 is tightly inserted into each of two adjacent string holes 102. String loop 106 connecting two vertical strings is received over engaging curved surface 204 of guiding groove 20.

As described above, when threading through each of guiding channel 142 of cleats 14, each of two vertical strings connected by loop 106 will firstly be suspended by each of bulges 30 and then enter into guiding channel 142 from inlet 144 without touching inner wall 148 thereof. Thus, the objects or advantages of the present invention can be achieved.

FIGS. 4 and 5 show an alternative stringing device 40 embodied according to the present invention. Device 40 is substantially the same as device 10 described above. Device 40 differs from device 10 solely with regard to the structure of cleat 42. In this embodiment, cleat 42 has a length being shorter than that of cleat 14 of device 10 so that when device 40 is mounted on racket 90, cleat 42 thereof is inserted into just a portion of string hole 102 of racket 90. This ensures that the diameter of the inlet of string hole 102 is smaller than that of the outlet thereof so that string chord threads through guiding channel 50 without touching inner wall 52 of cleat 42. Furthermore, in this embodiment, cleat 42 has a body 46 with an elongated opening 48. As shown in FIG. 5, this also ensures that string chord threading through guiding channel 50 will not touch inner wall 52 of cleat 42.

FIGS. 6 and 7 show a further alternative stringing device 60 embodied according to the present invention. Stringing device 60 includes an elongated base 62 and a cleat 64. Base 62 has a longitudinal upper surface 622, a longitudinal bottom surface 624 and a guiding groove 626 running longitudinally along upper surface 622. Guiding groove 626 has an open end 628 and a string engaging surface 630.

Cleat 64 is designed to be inserted into one of string holes 102. Cleat 64 extends downward from bottom surface 624 of base 62 and has a guiding channel 642 with an inlet 644 located on engaging surface 630, an outlet 646 opposed to inlet 644 and an inner diameter being larger than the outer diameter of racket string 100 so that it can thread therethrough.

In addition, string engaging surface 630 of guiding groove 626, as shown in FIG. 7, has a projecting area 632 with a curved bearing surface extending slightly into inlet 644 of guiding channel 642 so that the diameter of inlet 644 is smaller than that of outlet 646.

In this embodiment, device 60 is mounted on racket 90 in such a way that cleat 64 is tightly inserted into one of string holes 102 until that base 62 is leaned against the bottom surface of annular channel 946 of head frame 94.

When a racket is to be equipped with stringing device 60 to form a string opening, as shown in FIG. 7, there needs at least two devices 60 to be mounted on two adjacent string holes 102 in such a way that open end 628 of guiding groove 626 of each of devices 60 faces each other so that a loop 106 of string 100 connecting two vertical strings is received over each of string engaging surface 630 of base 62 and each of two vertical strings of loop 106 is suspended by projecting area 632 as threads through guiding channel 642 of cleat 64.

FIGS. 8 and 9 show a fourth embodiment stringing device 70 of the present invention. Device 70 is substantially the same as device 60 described above. Device 70 differs from device 60 solely with regard to base 72.

Base 72 has a longitudinal upper surface 722, a longitudinal bottom surface 724 and a guiding groove 726 running longitudinally along upper surface 722. Guiding groove 726 has a pair of opposing longitudinal open ends 728,730 and a pair of string engaging surface 732,734.

Device 70 also has a cleat 74 including a guiding channel 742 with an inlet 744 and an outlet 746. In this embodiment, inlet 744 is positioned between string engaging surfaces 732,734 of guiding groove 726 of base 72. Each of string engaging surface 732,734 of guiding groove 726 has a projecting area 736, 738 with a curved bearing surface extending slightly inwardly. This also ensures that the diameter of inlet 744 is smaller than that of outlet 746. The way to use device 70 is shown in FIG. 9. From this drawing, we can have a best understanding that each of two vertical strings connected by loop 106 will firstly be suspended by projecting area 736 or 738, then enter into guiding channel 742 from inlet 744 and lastly threads through guiding channel 742 without touching inner wall 748 thereof. Thus, the objects or advantages of the present invention can be achieved. 

1. A stringing device for a sports racket, comprising: an elongated base having opposing longitudinal side ends, a longitudinal upper surface and a longitudinal bottom surface opposed from said upper surface, each of said surfaces extending between said opposing longitudinal ends; said base further having a guiding groove running longitudinally along said upper surface thereof, said groove having an open end and a string engaging surface, said open end located at one of said side ends of said base; a cleat extending downward from said bottom surface of said base, said cleat having a guiding channel through which a racket string threads, said guiding channel having an inlet disposed on said string engaging surface of said guiding groove, an outlet opposed from said inlet, and an inner diameter being larger than the outer diameter of a string threading therethrough; and said string engaging surface of said guiding groove having a suspending portion corresponding to said inlet of said guiding channel for guiding a racket string to thread through said guiding channel without touching the inner wall thereof.
 2. The device according to claim 1, wherein said suspending portion is a projecting area.
 3. The device according to claim 2, wherein said suspending portion has a curved bearing surface.
 4. The device according to claim 2, wherein the diameter of said inlet is smaller than that of said outlet.
 5. The device according to claim 1, wherein said cleat extends at least partially through a string hole of a racket.
 6. A sports racket, comprising a head frame defining an opening, a plurality of string holes formed in said head frame toward said opening and at least a string device of claim 1, said string device being disposed on said head frame in such a way that said cleat thereof is at least partially and tightly inserted into one of said string holes.
 7. A stringing device for sports racket, comprising: an elongated base having opposing longitudinal side ends, a longitudinal upper surface and a longitudinal bottom surface opposed from said upper surface, each of said surfaces extending between said opposing longitudinal ends; said base further having a guiding groove running longitudinally along said upper surface thereof, said guiding groove having opposing longitudinal open ends, a first string engaging surface and a second string engaging surface, each of said open ends respectively corresponding to each of said side ends of said base, and each of said string engaging surface respectively corresponding to each of said open ends; a cleat extending downward from said bottom surface of said base, said cleat having a guiding channel through which a racket string threads, said guiding channel having an inlet disposed between said first string engaging surface and said second string engaging surface, an outlet opposed from said inlet, and an inner diameter being larger than the outer diameter of the racket string threading therethrough; said first string engaging surface of said guiding groove having a first suspending portions corresponding to said inlet of said guiding channel for guiding a racket string entering from one of said open ends of said groove to thread through said guiding channel without touching the inner wall thereof, and said second string engaging surface of said guiding groove having a second suspending portion opposing said first suspending portion for guiding a racket string entering from the other of said open ends of said groove to thread through said guiding channel without touching the inner wall thereof.
 8. The device according to claim 7, wherein each of said suspending portions is a projecting area.
 9. The device according to claim 8, wherein each of said suspending portions has a curved bearing surface.
 10. The device according to claim 8, wherein the diameter of said inlet is smaller than that of said outlet.
 11. The device according to claim 7, wherein said cleat extends at least partially through a string hole of a sports racket.
 12. A sports racket, comprising a head frame defining an opening, a plurality of string holes formed in said head frame toward said opening and at least a string device of claim 7, said string device being disposed on said head frame in such a way that said cleat thereof is at least partially and tightly inserted into one of said string holes.
 13. A stringing device for sports racket, comprising: an elongated base having opposing longitudinal ends, a longitudinal upper surface and a longitudinal bottom surface opposed from said upper surface, each of said surfaces extending between said opposing longitudinal ends; a pair of cleats respectively disposed at each of said opposing longitudinal ends of said base and extending downward from said bottom surface of said base, each of said cleats having a guiding channel through which a racket string threads, said guiding channel having an inlet near one of said opposing longitudinal ends of said base, an outlet opposed from said inlet, and an inner diameter being larger than the outer diameter of a racket string threading therethrough; said base further having a guiding groove running longitudinally along said upper surface thereof, said guiding groove having opposing longitudinal open ends and a string engaging surface disposed between said open ends for engaging and receiving a string which is looped thereover; and said string engaging surface of said guiding groove having a pair of suspending portions, each of said suspending portions disposed near each of said open ends and corresponding to said inlet of said guiding channel of each of said cleats for guiding a racket string to thread through said guiding channel without touching the inner wall thereof.
 14. The device according to claim 13, wherein each of said suspending portions is a bulge.
 15. The device according to claim 14, wherein each of said suspending portions has a curved bearing surface.
 16. The device according to claim 14, wherein the diameter of said inlet is smaller than that of said outlet.
 17. The device according to claim 13, wherein each of said cleats extends at least partially through a string hole of a sports racket.
 18. A sports racket, comprising a head frame defining an opening, a plurality of string holes formed in said head frame toward said opening and at least a string device of claim 13, said string device being mounted on said head frame in such a way that each of said pair cleats thereof is respectively at least partially and tightly inserted into one of an adjacent pair of said string holes. 